Chewing gums are generally comprised of a substantially water insoluble, chewable gum base such as chicle, is substitutes mixtures thereof and the like. Incorporated within this gum base may be plasticizers or softeners to improve the consistency and texture of the gum flavors and sweetening agents such as sugar or corn syrup, or for sugarless gums artificial sweeteners.
L-aspartyl-L-phenylalanine methyl ester (APM) is a dipeptide sweetening agent described in U.S. Pat. No. 3,492,131 and is a desirable chewing gum sweetening agent. Another attribute of APM is that it may be added in effective amounts to a normally sweetened sugar or sugarless chewing gum to produce longer lasting sweetness and flavor as disclosed in U.S. Pat. Nos. 3,943,258 and 3,982,023, which are herein incorporated by reference.
In the normal course of manufacture, shipment and storage of chewing gums, the product is often exposed to relatively high temperatures; i.e., 70.degree. F. to 100.degree. F. plus, for extended periods of time. The stability of APM is temperature sensitive. High temperatures induce the ester linkage to hydrolyze to the dipeptide aspartylphenylalanine. This dipeptide can then cyclize to the corresponding diketopiperazine. When this transition takes place, the sweetness of the APM is proportionately lessened. Thus, the effectiveness of APM in a chewing gum composition is greatly reduced when the gum is subjected to high thermal storage conditions. Therefore, it would be highly desirable if a simple system were devised whereby the decomposition of APM in chewing gum when stored at elevated temperatures could be greatly reduced.